The main goal of this project is to develop a model that integrates thermoregulatory control, sleep--wake state control and the control of respiration. This objective is driven by the growing body of evidence that suggests important roles for thermoregulation and sleep state control, in addition to cardiorespiratory control, as causal mechanisms for the Sudden Infant Death Syndrome. We have begun to address the above objective by implementing an existing thermoregulatory model of sleep, developed by Drs. McGinty and Nakao, in SIMULINK, a visually--oriented software package distributed by the Mathworks, Inc. (Natick, MA). Our existing model of respiratory control has also been implemented in SIMULINK. The next step in this project will be to establish interconnections between the two models that are consistent with empirical evidence in the physiological literature, and to adapt the model for application to infants.